 The study found that abstract marginal zone, MZ, B cells, identified as surface IgM highs IgD low CD, 23 low, the CD, 21 plus CD 38, B cells, have somatic hypermutations and recurrent sequences with intraclonal diversification. These features suggest that MZ B cells can expand and diversify in situ, and the study also found activation-induced citadine deaminase, aid, expressing B cells in the MZ. The data support the notion that MZ B cells are a special subset selected by in situ antigenic stimuli. This article was authored by Monica Colombo, Giovanna Caprona, Danielle Reverberi, and others.